1. Technical Field
This invention generally relates to machines for digging trenches adjacent railroad tracks and in particular to a machine and method for plowing a deep trench, for the installation of cable or pipe therein, adjacent the ballast of the railroad track.
2. Background Art
As far back as the early 1900's, ballast trenching machines have been used to periodically remove and replace the ballast of the railroad track bed. Typical of these machines are BUNNELL, U.S. Pat. No. 1,158,979, SPENO, U.S. Pat. No. 3,380,180 and JOHNSON, U.S. Pat. No. 1,455,494.
Bunnell teaches a railroad trenching machine designed for digging a trench in the ballast directly adjacent the railroad track. The invention consists of a railroad car having a conveyor belt type excavator attached to one side. Two major disadvantages to the excavator of Bunnell are first, the excavator is capable of trenching only within about three feet of either rail, and second, the machine can only be transported from excavation site to excavation site by rail.
Speno teaches a similarly located plurality of plowing tools for scarifying the ballast material directly adjacent the ends of the railroad ties. Speno's device is not capable of plowing deep trenches. Additionally, Speno's device is limited to trenching only in the ballast area, which is immediately adjacent the railroad track.
Johnson teaches a ditching machine which is capable of plowing trenches at greater distances away from the track and ballast. The device has a hinged rack which can be lowered into a coplanar position with the top of a railroad flat car and which trenching or plowing implements depend therefrom.
In laying utility lines, such as communication cables and the like, it is necessary to bury the cables at least three feet below ground surface, preferably 5-10 feet away from the track and ballast. It should be appreciated, that in plowing a three foot deep trench, great resistive forces are encountered. In fact, so great are these resistive forces that the moment created about the flat car actually distorts, loosens and bends the rails of the railroad track, using devices similar to that taught by Johnson. This moment is further exaggerated by the long moment arm necessary to plow trenches 5-10 feet away from the track.
Additional disadvantages to the device taught by Johnson include the lack of transportability of the specialized flat car and the non-steerable plow blades. While the plow blades of Johnson do appear to be depth adjustable, once adjusted they cannot be steered or easily readjusted to maneuver around an obstacle located along the railroad right-of-way.
Most utility line installers prefer not to use or own specialized railroad trenching cars. Obviously, this is because the railroad cars have to be transported by rail from excavation to excavation site and they must be stored in a rail yard when not in use. Most utility line installers use standard road excavation equipment when installing utility lines along railroad right-of-ways. This creates a substantial problem for the installer when faced with a narrow railroad right-of-way, such as those commonly found in mountainous areas and river valleys which do not have access roads or adequate working room beside the railroad track. The end result is that the utility line installation contractor must charge the utility companies, and ultimately the consumer higher prices to cover the costs of renting specialized equipment.
What is needed is a cost efficient apparatus and method for installing utility lines along railroad right-of-ways, be they narrow, wide or otherwise.
It is therefore an object of the present invention to provide a plowing apparatus for plowing trenches and method therefor, which is easily transported, cost efficient, does not interfere with the integrity of the railroad track rails and further does not require special railroad vehicles.